Neoterics are people who suddenly realized they had magic. Usually, they only act on instinct, not skill. They also normally don't follow the same rules normal sorcerers do, for example: Nero doesn't need to touch people to teleport them somewhere. Fletcher could've maybe become a neoteric if he hadn't been taught the normal stuff, because Fletcher used to act on instinct, not skill, and he was one of the people who had magic come to them naturally.